Method and device to improve start-up performance of a multi-layer optical disc

ABSTRACT

A method comprising recording data related to a start-up procedure on at least one of a plurality of recording layers disposed on an optical record carrier for reading back the recorded data during subsequent start-ups, the selection of the at least one recording layer based on properties of the at least one recording layer is disclosed. The technique reduces the optical record carrier start-up time and is useful for DVD, HD-DVD and BD recorders and/or players.

The subject matter relates to a method for improving start-upperformance of an optical disc and more specifically to a method forimproving start-up performance of a multi-layer optical disc.

US patent 2005/0002308 discloses a recorder for recording data on amulti-layer optical recording medium. Loading of the multi-layer opticalrecording medium into the recorder (i.e. starting the optical recordingmedium to be ready for recording) usually can take on an average about12 sec and can vary up to about 15 to 20 seconds. This can be quiteannoying for the end user.

It would be advantageous to have a method that can improve start-upperformance of a multi-layer record carrier. It would also beadvantageous to have a drive that can improve start-up performance of amulti-layer record carrier.

A method comprising recording data related to a start-up procedure on atleast one of a plurality of recording layers disposed on an opticalrecord carrier for reading back the recorded data during subsequentstart-ups, the selection of the at least one recording layer based onproperties of the at least one recording layer is disclosed.

A drive comprising a control unit arranged to record data related to astart-up procedure on at least one of a plurality of recording layersdisposed on an optical record carrier for reading back the recorded dataduring subsequent start-ups, the selection of the at least one recordinglayer based on properties of the at least one recording layer isdisclosed.

Furthermore, the method of recording data related to the start-upprocedure can be implemented with a computer program.

The above mentioned aspects, features and advantages will be furtherdescribed, by way of example only, with reference to the accompanyingdrawings, in which the same reference numerals indicate identical orsimilar parts, and in which:

FIG. 1 shows an example of a schematic picture of an example four layerrecord carrier;

FIG. 2 schematically illustrates repeated read behavior of an exampleBD-R disc at read powers of 0.7 mW, 0.9 mW, 1.0 mW and 1.2 mW;

FIG. 3 shows an example of a flowchart illustrating detailed steps ofthe method according to the present subject matter;

FIG. 4 schematically illustrates repeated read behavior of a layer in amulti-layer record carrier comprising a metal layer in the recordingstack and an example layer in a multi-layer record carrier without ametal layer in the recording stack; and

FIG. 5 shows an example of a schematic block diagram of an exemplarydrive used for recording/reading data from an example record carrier.

Referring to the example four layer optical record carrier 10 in FIG. 1,a plurality of recording layers L0, L1, L2 and L3 is formed above afirst surface of a substrate. A plurality of separation layers sp1, sp2and sp3 is disposed between the recording layers L0, L1, L2 and L3respectively. A cover layer c1 is disposed above the top recording layerL3. It is to be noted that the optical record carrier 10 has recordinglayers, which typically each consist of a stack of material layers. Thematerial layers in the optical record carrier 10 can be made of (forexample) ZnS, SiO2, Cu, Si and Ag. The stack of the recording layer L1,L2 and L3 consist of material layers ZnS, SiO2, Cu and Si. The materiallayers generally have a thickness of approximately about 5-15 nm. Therecan be no thick metal layer in the top recording layer L3 because itneeds to be transparent. The bottom recording layer L0 comprises asubstantially thick metal layer (e.g. thick Ag-mirror approximately100-150 nm thick). The thick metal layer can only be in the bottomrecording layer L0 because the bottom layer doesn't have to betransparent. It is noted here that only for illustration purpose a fourlayer optical record carrier is shown and it is possible to have anynumber of layers (e.g. two layers, three layers, four layers, sixlayers, eight layers).

The transmission through the top recording layer(s) has to be very highin order to record and read-out all the recording layers. The higher thenumber of recording layers, the higher will be the transmission neededby the top recording layer. As an illustrative example the transmissionof the individual recording layers that are required to reach aneffective reflection of 4% from each layer (4% reflection is the minimumreflection from each layer in the current Blu-ray disc standard (Systemdescription Blu-ray disc recordable format, Part 1, Basic formatspecifications; System description Blu-ray disc rewritable format, Part1, Basic format specifications)) are calculated. The results are shownin Table 1.

TABLE 1 Calculated transmission through each single individual recordinglayer Recording Reflection Transmission Effective layer (individuallayer), r (individual layer), t Reflection, R L3  4% 82% 4% L2  6% 74%4% L1 11% 63% 4% L0 27%  0% 4%

The data in Table 1 are calculated using the following formulas

R ₀=(t ₃ ×t ₂ ×t ₁)² ×r ₀

R ₁=(t ₃ ×t ₂)² ×r ₁

R ₂=(t ₃)² ×r ₂

R₃=r₃

where

-   -   t_(n) and r_(n) are the transmission and reflection from the        individual recording layers respectively; and R_(n) is the        effective reflectivity from the n^(th) layer in the optical        record carrier shown in FIG. 1.

It can be observed from Table 1 that the transmission of the toprecording layers L3, L2, and L1 need to be very high, i.e. 60-80%.Reaching such high transmission excludes the use of any metal layer inthe top stacks. Metal layers are often used as heat sinks to improvecooling of the recording stack. Therefore, unavoidably these upperlayers will also have very poor cooling performance.

In most optical disc standards (e.g. System description Blu-ray discrecordable format, Part 1, Basic format specifications; Systemdescription Blu-ray disc rewritable format, Part 1, Basic formatspecifications) the “repeated read stability” is specified. It is oftenspecified that one should be able to read-out the data 1.000.000 timesat a certain minimum read power without degrading the recorded data.

Referring to FIG. 2, the vertical axis represents the Jitter (in %) andthe horizontal axis represents the number of repeated read cycles. Itcan be seen that the higher the read power, the faster the jitterincreases (data degrades). During repeated read the radiation source(e.g. laser) slowly heats up the disc, which causes degradation of therecorded data. The better the cooling properties of the recording stack,the more stable the recording stack is during repeated read. Readstability is directly linked to the cooling properties of the stack.

Reading out data from a disc at speeds higher than 1× (4.92 m/s for BD)normally also requires the read power to be increased (to improvesignal-to-noise ratio). In practice this means that only discs with verygood read stability can be read out at higher speeds.

A method comprising recording data related to a start-up procedure on atleast one of a plurality of recording layers disposed on an opticalrecord carrier for reading back the recorded data during subsequentstart-ups, the selection of the at least one recording layer based onproperties of the at least one recording layer is disclosed.

A successful start-up is a critical performance indicator of a discplayer/recorder from the user's perspective. In a multi-layer opticalrecord carrier, different layers will have different properties.Recording data related to the start-up procedure on a recording layerbased on properties of the plurality of recording layers can improvestart-up performance as the start-up related data can be recorded on thelayer from which it can be accessed quickly. When the optical recordcarrier 10 loading in a recorder/player is fast, the user will have ahigher satisfaction index of the recorder/player (as compared to sloweroptical record carrier loading time).

Referring to FIG. 3, in step 302, one of the recording layers (i.e. oneof L0, L1, L2, and L3) is selected for recording the data related to thestart-up procedure based on certain properties of the recording layers.In step 304, the data is recorded on the selected recording layer.

In an embodiment, in recording the data related to the start-upprocedure, the property of the at least one recording layer is at leastone of repeated-read stability of the recorded data and read-out speed.Referring to FIG. 4, the horizontal axis represents the number ofrepeated reads and the vertical axis represents the jitter %. Opticalrecord carrier without the metal recording layer reaches about 10,000read cycles before the jitter starts to increase, whereas the opticalrecord carrier 10 (Cf. FIG. 1) with the metal recording layer is stableto over 1.000.000 read cycles. The thick metal layer (e.g. Ag-alloy) inthe optical record carrier 10 improves cooling of the stack;consequently the repeated-read stability of the first recording layer L0is very good. Hence, selecting an appropriate recording layer based onread-out speed and repeated read stability to record the start-uprelated data can improve start-up performance.

In a still further embodiment, in recording the data related to thestart-up procedure, one of the plurality of recording layers L0, L1, L2,L3 is a first recording layer L0 (Cf. FIG. 1) disposed above a firstsurface of a substrate and wherein the first recording layer L0 ispresent adjacent to a substantially thick metal layer. It is furthernoted here that the first recording layer L0 is the bottom recordinglayer (i.e. recording layer that is farthest from the radiation beamsource) as viewed from a recording/reading unit. Recording the datarelated to the start-up procedure on the first recording layer L0 isadvantageous since the first recording layer is the layer that has goodrepeated-read stability and read-out speed. Furthermore, since the firstrecording layer happens to be the layer with very good read stability,the start-up data can be read-out at higher speeds and hence can improvethe start-up performance. The first recording layer L0 has an addedadvantage that it offers higher data integrity.

In a still further embodiment, the data related to the start-upprocedure is at least one of table of contents of the recorded data,information on a menu structure of the recorded data and an executableapplication. This is advantageous since the said data is typicallyrequired in many applications directly after start-up.

Further, the information on the menu structure of the recorded datacomprises menu structure of a movie stored on the first recording layerL0 (Cf. FIG. 1). The streaming data (video and audio) is stored on thelayers L1, L2, L3 (Cf. FIG. 1) since they can be played back at lowerspeeds (e.g. 1× speed).

Furthermore, the method includes recording the data related to theexecutable application on the first recording layer L0 (Cf. FIG. 1) andrecording the remaining data associated with the executable applicationon the at least one of the plurality of recording layers L1, L2, L3 (Cf.FIG. 1) above the first recording layer L0. It is advantageous to recordthe executable application on the first recording layer L0, since it isread most often from the optical record carrier 10. The remaining dataassociated with the executable application such as database type datathat are less frequently read-out (only when required by the executableapplication) from the optical record carrier 10 can be recorded on therecording layers L1, L2 and L3. The executable application can be a java(registered trademark) application. This is advantageous since javaapplication may be executed by e.g. a BD drive directly after start-up.

In a still further embodiment, the optical record carrier is an opticalrecordable/re-writable record carrier such as DVD, Blu-ray disc andHD-DVD. The storage capacity of DVD's, Blu-ray discs and HD-DVD's isincreasing and four layer/six layer Blu-ray discs are expected to cometo the market. Hence, it would be advantageous to have a method that canaccess quickly the start-up related data and that can improve thestart-up performance of such discs.

Referring to FIG. 5, the optical record carrier 10 (Cf. FIG. 1) isconstant angular velocity (CAV) controlled or constant linear velocity(CLV) controlled by a spindle motor 52. An optical pick-up unit 54records data on the optical record carrier 10 by using laser light (at arecording power value) emitted form a laser diode. When the data is tobe recorded, it is supplied to an encoder unit 58 and the data encodedby the encoder unit 58 is supplied to a laser diode-driving unit 56. Thelaser diode-driving unit 56 generates a drive signal based on theencoded data and supplies the drive signal to the laser diode of theoptical pick-up unit 54. In addition, a control signal from a controlunit 54 is supplied to the laser diode-driving unit 56 so that therecording strategy and recording power are determined by the controlsignal. However, when the data is read from the optical record carrier10, the laser diode of the optical pick-up unit 54 emits laser light ofa read power (read power<record power), and the reflected light isreceived. The received reflected light is converted into an electricalsignal and a read RF signal is obtained. The read RF signal is suppliedto an RF signal-processing unit 50.

The RF signal-processing unit 50 comprises an equalizer, a binarizingunit, a phase-locked loop (PLL) unit, and binarizes the read RF signal,generates a synchronous clock, and supplies these signals to a decoderunit 57. The decoder unit 57 decodes data based on these suppliedsignals and outputs the decoded data as read data. The drive 500 alsoincludes a circuit (for data read-out) for controlling the focus servoor tracking servo by producing a tracking error signal or a focus errorsignal respectively, and a wobble signal formed on the optical recordcarrier 10 (e.g. for use in address demodulation or for controlling thenumber of rotations). The servo control structures are identical tothose in conventional drive systems and therefore are not described indetail.

The construction shown in FIG. 5 only illustrates portions related tothe general operation of the drive 500. The description and detailedexplanation of servo circuits for controlling the optical pick-up unit,the spindle motor, the slide motor, and the control circuits areomitted, because they are constructed in a similar manner as inconventional systems.

The control unit 59 is arranged to record data related to a start-upprocedure on at least one of a plurality of recording layers disposed onan optical record carrier for reading back the recorded data duringsubsequent start-ups, the selection of the at least one recording layerbased on properties of the at least one recording layer.

In an embodiment, in recording the data related to start-up procedure,the control unit is arranged to select the property of the at least onerecording layer from at least one of:

-   -   repeated-read stability of the recorded data; and    -   read-out speed.

In a further embodiment, the control unit 59 (Cf. FIG. 5) is arranged torecord the data on the first recording layer L0 (Cf. FIG. 1) disposedabove a first surface of a substrate wherein the first recording layerL0 is present adjacent to a substantially thick metal layer.

The drive 500 can be an optical drive such as DVD drive, Blu-ray discdrive and HD-DVD drive. Furthermore, a recorder or player (e.g. DVDrecorder and/or player, Blu-ray disc recorder and/or player) having thedrive 500 can reduce the time taken by the drive 500 to load the opticalrecord carrier 10 into the drive 500 (i.e. to be ready forrecording/reading).

Although the present subject matter has been explained by means ofembodiments using multi-layer Blu-ray discs, the subject matter isapplicable to all types of optical record carriers (HD-DVD, DVD, andCD). It is not limited to a two-layer one side disc, i.e., a dual layerdisc, and to a two-layer double side disc, i.e. a dual layerdouble-sided disc. A person skilled in the art can implement thedescribed embodiments of the method in software or in both hardware andsoftware. Other variations to the disclosed embodiments can beunderstood and effected by those skilled in the art of practicing theclaimed subject matter, from a study of the drawings, the disclosure andthe appended claims. The use of the verb “comprise” does not exclude thepresence of elements other than those listed in a claim or in thedescription. The use of the indefinite article “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The Figures and description are to be regarded as illustrative only anddo not limit the subject matter.

1. A method for recording data related to a start-up procedure on atleast one of a plurality of recording layers disposed on an opticalrecord carrier, the method comprising: selecting at least one recordinglayer based on one or more properties of the at least one recordinglayer, the properties of the at least one recording layer on which theselection is based including at least the repeated-read stability ofrecorded data; and recording the data related to the start-up procedureon the selected at least one recording layer for reading back therecorded data during subsequent start-ups.
 2. The method of claim 1,wherein said repeated read-stability comprises an ability to read datafrom the optical record carrier for a predetermined number of cycles ata predetermined read power.
 3. The method of claim 1, wherein theproperties of the at least one recording layer on which the selection isbased includes the read-out speed of the recorded data.
 4. The method ofclaim 1, wherein one of the plurality of the recording layers is a firstrecording layer disposed above a first surface of a substrate andwherein the first recording layer is present adjacent to a substantiallythick metal layer.
 5. The method of claim 1, wherein the data related tothe start-up procedure is at least one of: table of contents of therecorded data; information on a menu structure of the recorded data; andan executable application.
 6. A method for recording data related to astart-up procedure on at least one of a plurality of recording layersdisposed on an optical record carrier, the method comprising: selectingat least one recording layer based on one or more properties of the atleast one recording layer, the properties of the at least one recordinglayer on which the selection is based including at least the read outspeed of recorded data; and recording the data related to the start-upprocedure on the selected at least one recording layer for reading backthe recorded data during subsequent start-ups.
 7. The method of claim 6,wherein one of the plurality of the recording layers is a firstrecording layer disposed above a first surface of a substrate andwherein the first recording layer is present adjacent to a substantiallythick metal layer.
 8. The method of claim 6, wherein the data related tothe start-up procedure is at least one of: table of contents of therecorded data; information on a menu structure of the recorded data; andan executable application.
 9. A drive for recording data related to astart-up procedure on at least one of a plurality of recording layersdisposed on an optical record carrier, the drive comprising a controlunit configured to: select at least one recording layer based on one ormore properties of the at least one recording layer, the properties ofthe at least one recording layer on which the selection is basedincluding at least the repeated-read stability of the recorded data, andrecord the data related to the start-up procedure on the selected atleast one recording layer for reading back the recorded data duringsubsequent start-ups.
 10. The drive of claim 9, wherein the repeatedread-stability comprises an ability to read data from the optical recordcarrier for a predetermined number of cycles at a predetermined readpower.
 11. The drive of claim 9, wherein the properties of the at leastone recording layer on which the selection is based includes theread-out speed of the recorded data.
 12. The drive of claim 9, whereinthe control unit is configured to record the data on the first recordinglayer disposed above a first surface of a substrate and wherein thefirst recording layer is present adjacent to a substantially thick metallayer.
 13. The drive of claim 9, wherein the control unit is configuredto select the data related to the start-up procedure from at least oneof: table of contents of the recorded data; information on a menustructure of the recorded data; and an executable application.
 14. Adrive for recording data related to a start-up procedure on at least oneof a plurality of recording layers disposed on an optical recordcarrier, the drive comprising a control unit configured to: select atleast one recording layer based on one or more properties of the atleast one recording layer, the properties of the at least one recordinglayer on which the selection is based including at least the read outspeed of the recorded data; and record the data related to the start-upprocedure on the selected at least one recording layer for reading backthe recorded data during subsequent start-ups.
 15. The drive of claim14, wherein the control unit is configured to record the data on thefirst recording layer disposed above a first surface of a substrate andwherein the first recording layer is present adjacent to a substantiallythick metal layer.
 16. The drive of claim 14, wherein the control unitis configured to select the data related to the start-up procedure fromat least one of: table of contents of the recorded data; information ona menu structure of the recorded data; and an executable application.17. A non-transient computer readable media comprising a computerprogram code configured to interact with a control unit of a drive forrecording data on an optical record carrier, to perform a method forrecording data related to a start-up procedure on at least one of aplurality of recording layers disposed on the optical record carrier,the method comprising: selecting at least one recording layer based onone or more properties of the at least one recording layer, theproperties of the at least one recording layer on which the selection isbased including at least the repeated-read stability of recorded data;and recording the data related to the start-up procedure on the selectedat least one recording layer for reading back the recorded data duringsubsequent start-ups.
 18. A non-transient computer readable mediacomprising a computer program code configured to interact with a controlunit of a drive for recording data on an optical record carrier, toperform a method for recording data related to a start-up procedure onat least one of a plurality of recording layers disposed on the opticalrecord carrier, the method comprising: selecting at least one recordinglayer based on one or more properties of the at least one recordinglayer, the properties of the at least one recording layer on which theselection is based including at least the read out speed of recordeddata; and recording the data related to the start-up procedure on theselected at least one recording layer for reading back the recorded dataduring subsequent start-ups.